The present invention relates generally to improvements in the repair of pipes, conduits and the like, and it relates particularly to an improved method for repairing large diameter pipes or conduits with difficult access, such as underground sewer pipes or mains for water, gas and utilities.
Large diameter long pipes are widely employed in the transportation of fluids, both liquid and gaseous, such as sewer pipes, water mains, gas mains, and many other functionary pipes and conduits. Such pipes and conduits are usually accessible along their full lengths only with great difficulty, being either underground or in remote areas. Moreover, these pipes require frequent repair, since they are often ruptured, weakened and otherwise damaged. This damage is commonly a consequence of such occurrences and conditions as abrupt or radical changes in the differential pressure internally and externally of the pipe, ambient foundation or earth movements resulting from many causes, corrosion and erosion, and many other causes. In order to properly maintain the service afforded by underground pipe, any serious leaks must be promptly detected and repaired, and such repair generally requires the replacement of a long length of large diameter pipe, since the repair of a section of the pipe by welding, patching or otherwise, is usually unsatisfactory and very difficult. However, particularly in the case of underground pipe, the replacement of the pipe is difficult, expensive and highly time consuming and hence greatly inefficient, since structurally the pipe is still sound overall and except for weak areas and the points of rupture, still possess a long life expectancy. Not only is it necessary to dig a trench along and beyond the full length of the pipe section to permit its replacement, but the transport of the large pipe to and from the site is difficult, expensive and time consuming, as is the handling and manipulation of the pipe which necessitates the use of heavy crane equipment. Accordingly, the common practice in the maintenance and servicing of underground pipes and mains is expensive, time consuming and difficult and otherwise leaves much to be desired.